"Really and truly it comes down to the five food groups, the right quantity and the quality of food," she said.

"There's nothing special about maintaining a healthy weight. It's being sensible, reading labels, looking for the five star ratings - it's all out there."

Reducing your daily kilojoule count versus the 5:2 diet

A study by Austin Health and the University of Melbourne found the average weight loss after six months on a standard kilojoule reduction diet was 5.5kg.

It also found those on the popular 5:2 diet lost on average 5.3kg, showing both diets worked in the short-term.

Researcher Margie Conley said the study was conducted over six months in randomised 24 obese male war veterans aged 55-75.

"Interestingly, weight loss slowed at the three-month mark for both groups, which was when the dietitian follow-up tapered out, showing support may be the key element in continuing success," Ms Conley said.

The 5:2 diet involves eating only 2500 kilojoules on two non-consecutive days a week and then eating normally on the other five days.